Hot air furnace



4 Sheets--Sheet 1 Dec. 8, 1936. D. J. LUTY v HOT AIR FURNACE original Filed July 29, 1952 (ma Q D. J. LUTY HOT AIR FURNACE Dc. s, 193e.

4 sheets-sheet 2 Original Filed July 29, '1952 D. J. LUTY HOT AIR FURNACE Dec. 8, 1936.

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@Troma s D. J. LUTY HOT AIR FURNACE Dec. 8, 1936.

4 Sheets-Sheet 4 Original Filed July 29, 1932 ijgngw @5. ym Vil-J; a

Qomegg Patented Dec. 8, 1936 UNITED STATES PATENT- OFFICE Donald J. Luty, Detroit, Mich.. assigner to Wood Hydraulic Hoist & Body Company, Detroit, Mich., a corporation of Michigan Application July 29, 1932, Serial No. 625,642 Renewed November 18, 1935 8 Claims.

This invention relates to hot air furnaces and is concerned with a novel construction of furnace which is particularly adapted to have oil or gas, preferably, burned therein as a fuel, though in no sense limited to such fuel for operation, and wherein the products of combustion are carried in ilues underneath and lengthwise of the combustion chamber of the furnace in direct and intimate association with air around the ues which is thus heated, in addition to the heat given off from the Walls and top of the combustion chamber to the air within the enclosing casing which surrounds the combustion chamber, ues and the like.

'I'his results in a very greateconomy in that a much greater efiiciency in the absorption of heat units by the air is attained, and with a lesser proportion of the heat units being Wasted and escaping in the smoke pipe and stack which carries the products of combustion away from the furnace.

In addition the furnace construction may be directly designed to be used with an oil burning unit, the furnace and the oil burner being sold and installed together whereby the most emcient balance of the furnace capacity with the oil burner may be attained, this resulting in a still further economy of fuel consumption.

The invention is directed to many novel constructions, combinations and arrangements of parts for the' practical and effective attainment of the objects stated, as well as many others not at this time specifically enumerated, but which will be apparent as an understanding of the invention is had from the following description, taken in connection with the accompanying drawings. in which,

Fig. 1 is a transverse vertical section through the furnace of my invention.

Fig. 2 is a longitudinal vertical section therethrough.

Fig. 3 is a horizontal section taken substantially midway between the upper and lower sides of the furnace and also showing the air supply conduit and the smoke pipe conduit in section.

Fig. 4 is a fragmentary enlarged detail of the construction used for sealing certain joints between parts used in the construction.

Fig. 5 is a fragmentary enlarged horizontal section through the rear end portion of two of the flues through which the products of combustion circulate.

Figs. 6 and 7 are views similar to Figs. 1 and 2, respectively, of a different form of construction embodying the invention.

Fig. 8 is a horizontal section similar to that shown in Fig. 3 of said different form of furnace construction, and

Fig. 9 is a fragmentary vertical section substantially on the plane of line 9 9 of Fig. 7. 5

Like reference characters refer to like parts in the different gures of the drawings.

In the preferred form of structure, that shown in Figs. l to 5 inclusive, the outer furnace casing is of the usual material used for furnace casings. 10 .that is, sheet metal. and includes vertical sides I which at their upper edges have outturned flanges 2, joined with which are vupwardly convergingl sides 3, as shown in Fig. 1, having anges 4 at their lower edges bearing against and adapted l5 to be secured to the flanges 2 of the sides I. The upper edges of the inclined upper portions 3 of the casing havev a top 5 extending between them which has downwardly extending flanges 6 at its sides and ends, the flanges 6 at the sides being 20 secured to the parts 3 in any suitable manner. 'I'he furnace casing is completed by a front 'l and a back 8 secured to the side members I and 3 and the top 5 in any preferred or conventional manner. y The upwardly inclined upper portions 25 3 of the casing near their upper edges carry a plurality of outwardly extending sleeves 9 forming outlets for the heated air which is heated within the furnace casing and with which furnace pipes may be connected to lead to the sev- 30 eral rooms of a house or other building heated by the furnace. The furnace casing at its lower ,edges may rest upon a floor lli, such as the concrete noor in a basement, so that the casing provides an enclosure within which the air heat- 35 ing unit of the furnace is enclosed which is spaced from the sides and ends of the outer casing, and

it is in these spaces that the air is heated and circulates upwardly to the outlets at 9.

Within the furnace casing described a com- 40 bustion chamber for burning fuel is enclosed. It includes a front Il, a back l2, vertical side sections I3 and upwardly and inwardly inclined side sections I4 connected at their upper edges by an integral curved dome I 5 (see Fig. 1). There is 45 a bottom II to the combustion chamber located between the lower edges .of the sides Il whichy extends toward but stops a distance from the back I2, its rear portion being turned downwardly to make a vertical flange I 6a (Fig. 2). 'I'he front 50 Il has an opening therein in which a short cylindrical inlet I8 is secured, the same extending through the front 'l of the furnace casing. It is at this opening, through the cylinder I8, that the oil or gaseous fuel burner may be located. 55

or if other fuel is used, it is through this opening that the fuel is entered into the combustion chamber for burning.

The sides I3 of the combustion chamber terminate a short distance above the lower edges of the front II and back I2; and the lower edges of said front and back are located a distance above the floor I0 and are supported by horizontal fiues I9 of metal which extend the full length of the furnace casing at the lower portion thereof and are spaced apart from each other as shown in Fig. 1. The rear ends of the flues I9 (Fig. 5) are pressed together as indicated at 20 and welded together to make gas tightl connections. The lower part of the back 8 of the furnace casing is cut away to provide an opening of the height of the ilues I9 and of a length sulcient that the ends of all of the ues may pass therethrough. Preferably the air is forced into the furnace as by a blower or other equivalent pressure means.

The front ends of the flues I9 extend through an opening in the front plate 1 of the casing and are connected to a vertical plate 24, which has openings therethrough in direct communication with the front ends of the said ues I9. This plate is located at the front ofthe front plate 1 of the furnace casing and forms part of the breeching to the smoke pipe 25 which is designed to carry away the products of combustion to a chimney or other stack to which the pipe 25 leads. The flues I9 are supported on cross bars'26` located underneath the same and which are adjustable by means of adjusting screws 26a through their ends. for a short portion of its length between the back I2 of the combustion chamber and the rear edge of the bottom I6 of said combustion chamber, is cut away so that the products of combustion may pass downwardly'into the flues I9, move the length thereof toward the front and be delivered to the smoke pipe 25.

At the place where the products of combustion pass from the combustion chamber downwardly into the flues I9, it is necessary to provide a secure seal and one which will not be disturbed by -contraction and expansion nor result in warping of the parts of the combustion chamber through uneven expansions and contractions. To this end a rectangular frame 21 having U-shaped sides and ends is located upon and across the upper'sides of the nues I9, the downwardly extending flange I6a entering the forward channel of this frame and the lower edge portion of the back I2 of the combustion charnber entering the U-shaped rear channel of said frame, and the sides I3 at their rear end portions entering the shorter end channels of the' while it is in a plastic state and into the pack ing whereby, after the cement has set, a very secure gas tight seal is provided.

A rectangular plate 30 is located and secured within the frame covering the spaces between the ues I9 and having lopenings 3 I which register with the openings 32 made in the upper sides of the flues I9 for the passage of the products of combustion into the nues.

The construction also lends itself to the ready Each of the flues I9, at its upper side and,

installation of a shallow elongated water holding receptacle 33 to be mounted on and abovethe upper part of dome I5 of the combustion chamber. A water pipe 34, connected with a water main, extends lengthwise through the furnace casing above the receptacle 39, is closed at its free end, and has small openings in its underside from which water may drip into the pan, which water is vaporized to humidity the air.

It is also a feature of the present invention that the upper portion of the space between the furnace casing and the combustion chamber may be vertically divided. To this end angle supports 35 are secured at the outer sides of the walls I4 of the combustion chamber to which partitions 36 may be detachably connected. All of the angles 35 do not necessarily need to have the partitions 36 connected thereto at one time but a plurality there is liable to be undesired stresses set up productive of warping. 'I'he partitions divide the space enclosed between the furnace casing and direct the heated air to the outlets 9 between said partitions as is evident. The short cylinder 31, connected to the back I2 and extending through the back 9 of the casing and over which a covering cap is shown in Fig. 2, is for purposes of inspection, particularly of the burning flame when oil or gaseous fuel is used.

With this construction air forced through the conduit 22 may pass in part between the rear walls 8 and I2, but the major portion is forced forwardly between the flues I9. The products of combustion leaving the combustion chamber and traversing the length of the fiues I9 serve to heat this air very rapidly. This heated air passes forwardly and also upwardly between the ues and thence laterally as indicated byarrows in Fig. 1, and a portion of it is forced downwardly'and thence laterally passing upwardly between the sides of the enclosing casing and the combustion chamber, while all such air as is carriedforward to the front of the furnace then passes upwardly between the front walls 1 and II as indicated by the arrows. The air leaves the furnace casing through the outlets 9 and the warm air pipes connected thereto leading to the different rooms.

With this construction the air is subjected not only to the heated combustion l'chamber but is initially heated at and below the combustion chamber by the' heat given of! from the ues I9 with which the airis ilrst brought into immediate and intimate` contact. tion the high temperature gases, which are the products of combustion, instead of leaving directly from the combustion chamber to a smoke pipe, are required to pass through the flues I9 and there is a much greater opportunity to extract a greater portion of the heat from said gases and give it to the air,than if the gases did notpass through said flues. 'Ihis results in a very considerable economy in fuel comsumption, as is eviexpansion and contraction of materials. The" With such a construc temperatures of adjacent parts in most cases are substantially the same so that expansion of Aone part in association with others is substantially uniform with the part with which it contacts. For instance the expansion of the sides of the frame 21 is substantially uniform throughout its length. The expansion of the ends may not be thus uniform but the distance is so short that the amount of expansion is comparatively negligible whereby the seal described is not broken or disturbed. This construction, which is a preferred construction, has proved fully practical and serviceable and without defects in operation and secures in full measure the desirable result of great economy in fuel consumption.

In Figs. 6 to 9 inclusive, a somewhat modied form of construction is shown. The front and back plates I I and I2 of the combustion chamber are sealed in U-shaped cross bars 38 and 39 at their lower edges, using the same type of asbestos and cement seal as shown and described with reference to Fig. 4. The bottom plate I6c has an upturned flange I6d at its rear edge and the refractory material I l lies above the plate I6c which is also utilized as a cover for the flues which carry the gases of combustion to the smoke pipe, and is not spaced above such fines as the plate I6 is above the flues I9 in Fig. 1. The flues for carrying the gas and the intermediate spaces for the air to circulate through are bent up from a single continuous plate of metal in which the side edges are formed with U-shaped receiving seats 40 for the lower edges of the side vplates I3 of the comx bustion chamber, are then continued upwardly in sections 4I one along the inner side of each part I3, are then bent at right angles at 42 to lie directly underneath the plate I6c and are formed with a successive series of U-shaped bends making fiues 43 and alternate air conducting iiues 44. 'I'he upper ends of the flues 43 are closed by the plate I6c, the lower ends of said fiues being the integral lower ends of the U-shaped bends made in the plate, while the air flues 44 are open at their lower ends and at their upper ends are bounded by the upper bent portions which are made in the plate, as shown in Fig. 6.

As shown in Fig. 8, a. plate 45 lies over this flue construction between the rear sealing member 39 and the back 8 of the furnace casing. In saidplate, holes 46 are made, which provide connections between the air ues 44 and the space enclosed by the furnace casing between the walls 8 and I2. A plate 46a is located between the front sealing member 38 and the front of the furnace over the ues and it has openings which are in communication with like openings made in the upper ends of the air ues 44, as shown in Fig. 9, for a part of the warm air, forced through the ues, to pass upwardly between the front wall 1 of the casing and the front wall II of the combustion chamber; and of course other warm air circulates downwardly and laterally from the lower open sides of the air flues 44.

In addition to the air which is forced into the furnace casing as described, the rear side 8 of the furnace casing at each side of the flues, may have openings therein which are adapted to be closed by dampers 41 (Fig. 8) pivotally mounted and each having an arm 48 connected thereto from which an operating rod 49 extends outwardly through a side I of the casing, whereby the dampers may be opened or closed. In open position air will pass from the cold air inlet flue 22 directly into the furnace casing at each side between the sides I and I3 of the structure.

'Ihe construction just described is a form of construction operating upon substantially the same principle as that rst described. 'I'he principle of operation, that of forcing the heated products of combustion downwardly and longitudinally through flues located underneath the combustion chamber, is preserved with a consequent economy of operation and fuel consumption.

A hot air furnace of the. constructions described, as previously stated, is very economical with respect to fuel consumption, is simple to construct, is inexpensive and is particularly efIicient in all respects. The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. A hot air furnace comprising an outer enclosing casing, cross means in the lower portion of the casing, adjustable means supporting said cross means for adjusting and leveling the same, a plu-v rality of flues spaced from each other transversely and lying longitudinally of the casing between the front and back thereof, each of said flues having an opening therein at its upper side, an enclosed combustion chamber within the casing spaced from the walls thereof and resting upon said ues having an outlet at its lower portion to pass products of combustion therefrom into the flues, means for excluding the products of combustion from between the ues located at said combustion chamber outlet, means for carrying air to and between the ues at the rear ends thereof, and means for carrying the products of combustion from said ues at the forward ends thereof.

2. A hot air furnace comprising, an outer enclosing casing of sheetmetal, a combustion chamber having walls substantially parallel with the walls of said casing located within the casing and spaced therefrom, a plurality of spaced ues located horizontally and lengthwise of and at the lower part of the casing below said combustion chamber, said combustion chamber having a bottom extending rearwardly from its front end toward but terminating short of the rear wall of the combustion chamber thereby providing an outlet from the combustion chamber, said flues in the upper sides thereof having openings in communication with said outlet, a plate located across said ues at said outlet having openings in communication with the openings in the flues, a conduit at the lower reai` portion of the casing carrying air to and into the spaces between said ues, and a pipe at the lower front portion of the casing into which the front ends of said fiues extend to deliver products of combustion passing through the ues to saidpipe.

3. Ina hot air furnace, a sheet metal outer casing having spaced apart front and back and spaced apart vertical side walls, the upper portions of which are inclinedinwardly toward each other, and a top completing the casing located between the upper edges of the side walls and the front and back, said casing having outlets at its upper end in each side, a combustion chamber having vertical front and back, vertical side walls and a dome having sides inclined upwardly and inwardly toward each other and integrally connected by a curved section, a bottom for said combustion chamber located a short distance above the lower edges of said front and back and extending rearwardly, a plurality of horizontal nues,

spaced apart from each other, lying the full length of said casing, underneath the combustion chamber and upon which the front and back of said combustion chamber rest, thereby spacing the flues from the bottom of the combustion chamber,

said flues at their upper sides having openings in communication with the combustion chamber, means for preventing passage of products of combustion between the ilues and permitting said passage into said fiues, and means for carrying air into the casing at and between the rear ends of the flues, -as specified.

4. 'A hot air furnace comprising, an outer enclosing casing, an inner enclosed combustion chamber having an outlet opening at its lower portion, spaced lues located longitudinally of the casing below the combustion chamber and provided with openings in alinement with said combustion chamber outlet, means for closing the space between the several openings and the periphery of the outlet, means for rigidly attaching the spaced iiuesaround the outlet opening and supporting means extending from the inner enclosed combustion chamber adapted to slidably engage the several flues whereby expansion of the combustion chamber may readily occur.

5. A hot air'furnace of the class described comprising, an outer casing, an enclosed combustion chamber having a short inlet slidably extending through the outer casing whereby fuel may be fed thereinto, said combustion chamber having an outlet at its lower portion, connecting means around said outlet, ues extending underneath the bottom portion of the combustion chamber, said flues having openings adjacent the combustion chamber, means for rigidly attaching the ues to the connecting means so that the openings therein connect with the outlet opening in the lower portion of the combustion chamber, said flues being slidably mounted` at all other points with respect to the combustion chamber whereby they may readily expand.

6. A hot air furnace comprising a plurality of substantially horizontally disposed flues arranged in spaced relation, a combustion chamber arranged above said ilues, means for conducting products of combustion solely from one end of said combustion chamber downwardly to said fines, and means for introducing air to be heated to the spaces between said ues, said last mentioned means being located adjacent the said first means whereby the incoming air will contact said flues at their hottest point.

7. A hot air furnace comprising a plurality of substantially horizontally disposed fiues, arranged in spaced relation, a combustion chamber arranged above said flues and in direct heat conductive engagement therewith, a casing enclosing said flues and combustion chamber and spaced from said combustion chamber, 'means for conducting the gaseous products of combustion down- .wardly to said fiues, means for conducting air to the spaces between said iues, and means 'for conducting said air upwardly from said spaces to the space between said combustion chamber and casand means for conducting said air from the spaces between said fines to the space between said casing and said combustion chamber.

DONALD J. LUTY. 

